'Li-fi' micro-lights could revolutionise communications

By Sofia Mitra-Thakur

Published Friday, January 25, 2013

Tiny LED lights are being developed that could deliver Wi-Fi-like internet.

Over the next four years, with Engineering and Physical Sciences Research Council (EPSRC) funding, a consortium of UK universities led by the University of Strathclyde will be developing this innovative technology to help unleash the full potential of ‘Li-Fi’ – the transmission of internet communications using visible light rather than the radio waves and microwaves currently in use.

Although the potential possibilities offered by Li-Fi are already being explored all over the world, this EPSRC-funded consortium is pursuing a radical, distinctive vision that could deliver enormous benefits.

Underpinning Li-Fi is the use of light emitting diodes (LEDs), a rapidly spreading lighting technology which is expected to become dominant over the next 20 years.

LEDs flicker on and off imperceptibly thousands of times a second.

By altering the length of the flickers, it is possible to send digital information to specially adapted PCs and other electronic devices – making Li-Fi the digital equivalent of Morse Code.

This would make the visible part of the electromagnetic spectrum available for internet communications, easing pressure on the increasingly crowded parts now used.

But rather than developing Li-Fi LEDs around 1mm2 in size, which other researchers around the world are concentrating on, the EPSRC-funded team is developing tiny, micron-sized LEDs which potentially offers a number of major advantages:

Firstly, the tiny LEDs are able to flicker on and off 1,000 times quicker than the larger LEDs, which means they can transmit data more quickly.

Secondly, 1,000 micron-sized LEDs would fit into the space occupied by a single larger 1mm2 LED, with each of these tiny LEDs acting as a separate communication channel.

A 1mm2 sized array of micron-sized LEDs could therefore communicate 1,000 x 1,000 (i.e. a million) times as much information as one 1mm2 LED.

Each micron-sized LED would act as a tiny pixel, so one large LED array display (e.g. used to light a living room, a meeting room or the interior of an aircraft), could also be used as a screen displaying information at exactly the same time as providing internet communications and the overall room lighting.

Professor Martin Dawson of the University of Strathclyde, who is leading the initiative, said: “Imagine an LED array beside a motorway helping to light the road, displaying the latest traffic updates and transmitting internet information wirelessly to passengers’ laptops, netbooks and smartphones.

“This is the kind of extraordinary, energy-saving parallelism that we believe our pioneering technology could deliver.”

Eventually, it could even be possible for the LEDs to incorporate sensing capabilities too.

For example, your mobile phone could be equipped with a flash that you point at a shop display where everything has been given an electronic price tag, and the price of all the items and other information about them would show up on your phone’s display.

The research team will harness LEDs made from gallium nitride, a material whose properties are ideal for high-power, high-frequency applications.

The visible part of the electromagnetic spectrum is 10,000 times bigger than the microwave part of the spectrum. Li-Fi could therefore make a huge contribution to enabling growing demand for internet communications to be met in future.

Professor Dawson said: “The Universities of Cambridge, Edinburgh, Oxford and St Andrews are all working with us, bringing specific expertise in complementary areas that will equip the consortium to tackle the many formidable challenges involved – in electronics, computing and materials, for instance – in making this vision a reality.

“This is technology that could start to touch every aspect of human life within a decade.”